1. Field of Invention
This invention relates to devices for collecting biological samples. The devices are particularly suited for collecting exudates, fluids and columnar epithelium from the endocervix.
Swabs with rough, woven surfaces have been used historically to collect specimens for the analysis of infectious disease from various anatomical sites, including the throat, urethra, vagina, endocervix, rectum and skin. Materials such as cotton, rayon, dacron and nylon were commonly employed as swabs because they absorb significant volumes of fluid and provide for some scraping action.
Swabs are, however, unsuitable for elution methods and for the preparation of direct smears. The absorption and retention properties of swabs and the release properties of swabs are mutually exclusive. A swab made from a material that readily absorbs fluid generally has poor release properties. Therefore, material which is transferred from such a swab to a glass slide contributes significantly to poor assay sensitivity. Furthermore, attempts to elute absorbed material from swabs have shown that, even with the addition of reagents such as detergents, salts and the like to aid elution, the absorption of biological materials by swabs is difficult to reverse. Furthermore, reagents used to chemically actuate elution can actually contribute to the problems associated with loss of antigenic integrity of the subject analyte, toxicity to indicator cell lines in culture tests and an increase in background noise or interference in the assay.
A second problem area relates to specimen quality in terms of how the test material is temporarily absorbed by the swab. For example, as a swab is inserted into the endocervix, it will begin to absorb lumenal material first depending on the viscosity and volume of the contacted material. Thereafter, cellular material and material lining the surface of the endocervix is scraped off as the swab is rotated. The cellular material and the material lining the surface of the endocervix may or may not be absorbed by the swab. Low viscosity lumenal material will reside in the interior of the swab to a greater degree than the superficial epithelial cells and adherent analyte. When the collected material is transferred directly to a glass slide only that part of the specimen on the outside of the swab is transferred. Whereas, if elution is used, extraction of lumenal material from the interior of the swab may also be poor. In those instances wherein lumenal mucus is heavy, access of material to the interior of the swab may be blocked off, thereby effectively stopping absorption early on. Furthermore, the outside of a swab cannot scrap effectively, if covered by a cushion of mucus. The performance of the swab is, therefore, highly dependent on the qualitative and quantitative content of the specimen at the time of sampling. The stage of a disease, such as, for example, chlamydia, and other physiological factors may markedly effect the qualitative content of the specimen at the site.
Metal or plastic bacti loops are often used in place of swabs to obtain urogenital samples for testing sexually transmissible diseases. Metal loops have been used primarily in Europe but for safety reasons are not generally considered acceptable in the United States. The plastic loops available in the United States cannot, in the absence of copious exudate, be relied on to gather sufficient material or to provide for a scraping action as does the swab or, to a lesser extent, the metal loop.
A device called a cytobrush has been used in place of a swab for collecting endocervical samples in nonpregnant patients. The device resembles a miniature bottle cleaning brush and has bristles of various lengths. During collection, biological material including columnar cells adhere to the bristles.
There is a need, therefore, for a collection device that will allow scraping of a surface to collect material without cutting, and will retain the sample material, including both lumenal and scraped material, during and after collection of the specimen. Additionally, such a device will provide consistent quantitative sampling and substantially complete quantitative release during elution.
2. Description of the Prior Art
U.S. Pat. No. 4,020,847 discloses a rotating cutter catheter with a straight cutting edge configured to cut only protruding irregularities along non-desquamating endothelial lining of blood vessels without sampling the intact, normal surface. U.S. Pat. No. 2,437,329 discloses a surgical instrument for curetting having a longitudinal opening formed in the wall of the tube. One lip of the longitudinal opening is everted to form a curetting member. A rectal scraper is disclosed in U.S. Pat. No. 2,495,794. U.S. Pat. No. 3,626,470 discloses a diagnostic device for obtaining cytological samples. The device has an elongated handle with a flexibly coupled platform with a spongelike pledget. A cutting tool and a biopsy punch as disclosed in U.S. Pat. Nos. 2,876,777 and 2,778,357, respectively. Inoculation devices are disclosed in U.S. Pat. Nos. 3,850,754, 3,455,788 and 3,234,107.
Curettes are disclosed in U.S. Pat. No. Des. 275,127 and 219,252. Inoculating loops are disclosed in U.S. Pat. Nos. Des. 274,464 and 271,519. A surgical aspiration catheter and a disposable loop are disclosed in U.S. Pat. Nos. Des. 264,246 and 251,013, respectively.